Aphid Alert
No. 6, 2000
16 July
Published cooperatively by
departments of Entomology & Plant Pathology,
College of Agricultural, Food and Environmental
Sciences, University of Minnesota,
the University of Minnesota Extension Service,
and the State Seed Potato Programs of
Minnesota and North Dakota
Funding provided by:
Minnesota State Legislature &
United States Department of Agriculture,
Cooperative State Research, Education and Extension Service,
Integrated Pest Management Program,
North Central Region
WWW address: http://ipmworld.umn.edu/alert.htm
Update:
Summary of virus vector situation through 18 July.
Comparison of green peach aphid flight activity 1992-1994 and 1998-2000
Aphid captures reported by location for week ending 18 July. Data reported here only for locations with links.
| MINNESOTA |
|||||
| Baker 17 July |
Climax 18 July |
Crookston 18 July |
Gully 17 July |
Hollandale 18 July |
Karlstad 18 July |
| Little Falls 18 July |
Morris 18 July |
Rice 18 July |
Rosemount |
Thief River Falls 18 July |
Williams |
| NORTH DAKOTA |
|||||
| Cando 14 July |
Hoople 14 July |
Linton 18 July |
Mandan 18 July |
Minot |
Rolette 14 July |
| Walhalla 14 July |
|||||
| WISCONSIN |
|||||
| Antigo 17 July |
Rhinelander 17 July |
||||
| SOUTH DAKOTA | |||||
| Watertown 18 July |
|||||
| NEBRASKA | |||||
| Cody 17 July |
|||||
Update: Summary of virus vector situation
through 18 July.
Captures of winged aphids in the Aphid Alert network traps remained low during the week ending 18 July. Minnesota and North Dakota locations averaged less than 3 aphids of all species per trap and less than 0.1 green peach aphid per trap. Total aphids and green peach aphid were both about twice as abundant as they were in the previous week. Total aphid captures in the fifth week of 2000 are about 1/3 of that during the same week of 1998 and 1999 and green peach aphid captures are 1/2 that of 1998 and 1/7 that of 1999.
What are aphid populations going to do for the rest of the year? Yogi Berra observed that "Prediction is very hard, especially when it is about the future." Aphid populations are lower on cereals or canola than in 1998 and 1999. However, both crops are nearing maturity and this will cause the aphids that are there to fly. We expect an increase in aphid flight activity in the near future. There are also substantial populations of green peach aphids on wild mustard. The surface flooding that occurred in many areas drowned out much cropland permitting wild mustard and other weed hosts of green peach aphid, e.g., redroot pigweed to take over. Scouting for green peach aphid should be focused on the margins of potato fields since this is where initial colonization occurs.
Potato leafhoppers are again abundant in the Red River Valley. The adults are not abundant enough to cause direct injury, but potato fields should be scouted for the nymphs. We have shown that reduced rates (1/4X) of dimethoate or Asana will give excellent leafhopper control without flaring aphids. Aster leafhoppers are present at very high densities. Aster leafhopper does not colonize potato, but this species vectors aster yellows (the causal agent of "purple top") which has been associated with dark chips.
Visit Jeff Miller's Late Blight Site
Captures of PVY vectors (other than green peach aphid) per trap, 1998-1999
Trap locations in 2000
Update on Aphid Alert project
Leafhopper Alert